β-tricalcium phosphate (TCP) is an important biomedical material but the synthesis of β-TCP with uniform nanostructure still remains a challenge. We report that β-TCP porous nanospheres could be prepared feasibly by a solvothermal method, in which trimethyl phosphate was used as the organic phosphorus source. The as-prepared 120 nm nanospheres were assembled by 15–25 nm nano building blocks with a multilevel structure, resulting in multiple pore size distributions. As a result, they have excellent cytocompatibility, high drug loading and protein adsorption capacities, and sustained release behaviours. It follows that the uniform porous β-TCP nanospheres are more promising for applications in biomedical fields.